"In a land of only 18 million people, almost everyone knew someone, or knew someone who knew someone, who was among the 500 or so people in the small waterfront historic site at Port Arthur that day", Sullivan wrote.

"The reason police went to the property was from a telephone call which we've recorded", said Dawson, who would not comment on the identity of the caller.

Commissioner Dawson said the small Osmington community would be reeling but was confident it would rally together.

The grandfather is suspected to have gunned down six members of his own family at a Margaret River farm yesterday before turning the gun on himself, News Corp is reporting.

Most recently Democratic representative Eric Swalwell (Calif.) penned an op-ed calling for a gun confiscation scheme similar to Australia's in the United States.

Police did not immediately identify the dead, saying they were still trying to locate next of kin, but authorities believe all seven people who were slain were residents of the property, the newspaper reported.

Former local councillor Felicity Haynes, who lives on a neighbouring property, said the family involved were "caring neighbours". Two firearms were also found at the scene.